[Amps] questions about hi pot tester

[Commander John]

Hi All
  I need a hi pot tester.  Three years ago I set out to build one and am no where near done.
  So I am looking to buy a working unit.
   
  I am in need of what to look for in purchasing a used unit.  I am not a rich guy so cheap is in.  In checking ebay I noted some old ones with voltage to about 6kv and using little light bulbs to indicate leakage current.  Suggestions please.
   
  Thank you
  john w9zy